Bioreactor system

ABSTRACT

Disclosed herein are bioreactor systems and methods of utilizing said systems.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/374,000, filed Aug. 16, 2010, which is hereby incorporated herein byreference in entirety.

BACKGROUND OF THE INVENTION

The ability to culture in vitro viable three-dimensional cellularconstructs that mimic natural tissue has proven very challenging. One ofthe most difficult of the many problems faced by researchers is thatthere are multiple dynamic biochemical and mechanical interactions thattake place between and among cells in vivo, many of which have yet to befully understood, and yet the complicated in vivo system must beaccurately modeled if successful development of engineered tissues invitro is to be accomplished. The ideal in vitro system should accuratelymodel the mechanical environment as well as the essential cellularinteractions found during in vivo development while providing purity ofthe desired product construct so as to enable utilization of theproduct, for instance as transplantable tissue.

Many existing culture systems are simple well plate designs that arestatic in nature and do not allow for manipulation of the localenvironment beyond the gross chemical inputs to the system. As such, thedevelopment of more dynamic culture systems has become of interest,because it introduces the possibility of advantageously changing thelocal environment over the course of a cell culture experiment. However,known dynamic systems have not been widely implemented in the field ofcell culture, as they are labor intensive, cost prohibitive, haveconfigurations which limit their experimental flexibility and lackinter- and intra-lab comparability because there is no universalstandard procedure.

In another aspect, there are many advantages to culturing cells in 3D(as opposed to historic 2D cell culture) that are being increasinglyappreciated with a societal focus on higher and higher fidelity in vitromodels of in vivo human physiology. One of these many advantages relatesto the cultured cells' phenotype. It is known that conventional 2Dculture of cells is often associated with a loss of phenotype and celldamage while 3D culture has been shown to retain cell phenotype. SeeMayne, R. et al (1976) PNAS, 73, 5; Brodkin, K. R. et al (2004)Biomaterials, 25, 28; Elowsson, L. (2009) PhD Thesis (University ofSheffield, UK); Benya, P. D. and Schaffer, J. D. (1982) Cell, 30, 1;Bonaventure, J. et al (1994) Experimental Cell Research, 212, 1; andOsiecka, I. et at (2008) Molecular Medicine Reports, 1, 6. However,current technology does not allow for the exploitation of 3D cultureadvantages requires innovation to address the practical difficulties of3D culture when compared to its simpler, 2D cell culture, predecessor.

One such exemplary technology lag area has been the process of cellpassaging, in which a relatively small number of cells are repeatedlydoubled for the sole purpose of creating a large number of cells (e.g.,to achieve the number of cells necessary for a particular experiment).As one skilled in the art will appreciate, passaging cells in 2D isconvenient and ubiquitously standardized. Additionally, duringconventional passaging cells in 2D procedures, most cells enter into astate of rapid proliferation which decreases the time necessary toachieve the desired large number of cells. As one skilled in the artwill appreciate, in conventional 2D passaging, cells respond to thestiffness of the material on which they attach. See, Attachment A,Micro- and Nanoengineering of the Cell Microenvironment, Technologiesand Applications (Engineering in Medicine & Biology), All Khademhosseini(Editor)).

Relative to tissues found in the body formed from organic materials,tissue culture lab ware is typically formed from stiff materials. Forexample and without limitation, the moduli of soft mammalian tissuesranges from about 100 Pa to about 950 kPa. Exemplary moduli of softmammalian tissues include:

TABLE 1 A summary of elastic moduli of several different tissues.Experimental elastic moduli of a variety of tissues. including theanimal of origin of the tissue, and the testing modality used todetermine the modulus. When multiple stiffness values were available.the value at the lowest strain rate and lowest pre-strain was used toapproximate the “resting stiffness” of the tissue Testing Elastic Tissuetype Animal method modulus Ref Achilles' tendon Rat Tension 310 Mpa 15Articular cartilage Bovine Compression 950 kPa 86 Skeletal muscle RatTension 100 kPa 87 Carotid artery Mouse Perfusion 90 kPa 88 Spinal cordHuman Tension 89 kPa 89 Thyroid cancer^(a) Human Compression 45 kPa 16Spinal cord Rat Tension 27 kPa 90 Cardiac muscle Mouse Tension 20-150kPa 91 Skeletal muscle Mouse AFM 12 kPa 13 Thyroid Human Compression 9kPa 16 Lung Guinea pig Tension 5-6 kPa 5 Breast tumor Human Compression4 kPa 7 Kidney Swine Rheology 2.5 kPa 92 Premalignant breast^(b) HumanIndentation 2.2 kPa 14 Fibrotic liver Human Compression 1.6 kPa 93 LiverHuman Compression 640 Pa 93 Lymph containing Human Vibrational 330 Pa 17metastases resonance Brain Swine Indentation 260-490 Pa 94 Lymph NnodeHuman Vibrational 120 Pa 17 resonance Mammary gland Human Compression160 Pa 7 Fat Human Indentation 17 Pa 14 ^(a)Thyroid papillaryadenocarcinoma. ^(b)Mammary ductal carcinoma in situ. 2 | Soft Matter,2006, 2, 1-9 This journal is  © The Royal Society of Chemistry 2006See, Soft Matter, 2007, 3, 299-306, DOI: 10.1039/b610522j“Softbiological materials and their impact on cell function” Ilya Levental,Penelope C. Georges and Paul A. Janmey.

Exemplary tissue culture lab ware formed from polystyrene has an elasticmodulus of 3-3.5 GPa, which is higher than the modulus of tissues formedfrom organic materials but not as high as the elastic modulus of bone (9GPa). In this aspect, bone is a composite made up of inorganic mineralswith high bulk moduli and organic materials which are much softer, andthe contribution of the inorganic materials increases the moduluscorrespondingly. See, Journal of Biomedical Materials Research Part AVolume 67A, Issue 3, Pages 886-899 Published Online: 20 Oct. 2003, (bulkhydroxyl apatite modulus of 34-117 GPa).

Currently there are no commercially available products designed for 3Dcell passaging. Published research on this topic to date has exploredaspects of the potential use of 3D hydrogels (of hyaluronic acid andpoly(NIPAM) respectively) for 3D cell passaging and has shown benefitsof phenotype retention. See, TERMIS-EU 2010 Oral Presentation“Thermally-responsive Polymers for 3D Chondrocyte Culture;” and U.S.patent application Ser. No. 11/473,870 to Singh, which is incorporatedherein by reference in its entirety. However, hydrogel matrices are notin the stiffness range of tissue culture polystyrene or bone.

What is needed in the art is a method for culturing cells in a dynamicenvironment in which the physical and biochemical conditions can beadvantageously changed over the course of time. Moreover, what is neededis a system in which cells can be developed to form a three-dimensionalconstruct, while maintaining the isolation and purity of the developingproduct cells. In another aspect, what is needed is a material andmethod for 3D cell passaging that the use of a stiff culture material ina 3D cell culture environment while maintaining a desired level ofphenotype retention.

SUMMARY

In one aspect, the present invention is directed to a bioreactor system.The disclosed bioreactor system can comprise a single or a multipleculture system. In one aspect, a bioreactor system of the invention cancomprise at least one culture chamber defining an inlet, an outlet, anda port that are in communication with an interior volume of the at leastone culture chamber. In one non-limiting example, the at least oneculture chamber comprises a first culture chamber and a second culturechamber. In this aspect, the first culture chamber defines a first inletand a first outlet that is configured to allow fluid to selectively flowthrough the interior of the first culture chamber. In a further aspect,the first culture chamber defines a first port that is in communicationwith the interior of the first culture chamber. The second culturechamber defines a second inlet and a second outlet that is configured toallow a second fluid to selectively flow through the interior of thesecond culture chamber. In a further aspect, the second culture chamberdefines a second port that is in communication with the interior of thesecond culture chamber.

In another aspect, the system can also comprise a membrane, which can bepositioned, for example and without limitation, between the respectiveports of adjoining first and second culture chambers. The membrane canbe semi-permeable and can have a porosity that is configured to allowpassage of cellular expression products through the membrane, butprevent passage of the cells, which are disposed therein either chamber,through the membrane. In one embodiment, the membrane can be formed of amaterial, for example and without limitation a polycarbonate, which candiscourage cellular attachment to the membrane.

In a further aspect, the bioreactor systems of the invention cancomprise a cellular anchorage in one or both of the respective culturechambers. Suitable cellular anchorage can be formed of multiple discretescaffolds or single continuous scaffolds. Multiple discrete scaffoldscan be maintained within a culture chamber through utilization of aretaining mesh that can hold the scaffolding materials within thechamber and prevent the loss of the scaffolding materials through theoutlet of the culture chamber.

In one aspect, a cellular anchorage can be maintained at a predetermineddistance from the membrane that separates the chambers. In one aspect,this predetermined distance can be selected to effect prevention orminimization of attachment of cells to the membrane and can act tomaintain the physical isolation of different cell types within theirrespective culture chambers.

The bioreactor system can also be capable of incorporating additionalculture chambers that can be in biochemical communication with one orboth of the other two culture chambers. For instance, the at least onechamber can further comprise a third chamber that can be configured toselectively house cells that can be selectively positioned inbiochemical communication with the one or more of the system culturechambers, optionally with a membrane separating the first and thirdchambers, though this aspect is not a requirement of the system.

It is contemplated that, in operation, the bioreactors and the cellsdisposed therein can optionally be subjected to at least one mechanicalstimuli. For example and without limitation, pressurized fluid perfusionthrough a culture chamber can subject developing cells to shear stress;an adjacent pressure module can be utilized to subject the interior of aculture chamber to hydrostatic loading, and the like.

It is also contemplated that the bioreactors of the system can be usedfor growth and development of isolated cells in various differentapplications. For instance, three-dimensional cellular constructs can beformed including only the cells that are isolated in one of the culturechambers of the reactor system. In one exemplary aspect, a culturechamber can be seeded with undifferentiated cells, and the method cancomprise triggering differentiation of the cells via the biochemicaltriggers provided from the cells of the second culture chamber.

In a further aspect, it is contemplated that for tissue passaging, amaterial composition comprising two or more materials can be used. Inone example, the material composition can comprise a stiff culturematerial having substantially large porosity into which a soft materialhas been introduced. In one example, and without limitation, the stiffculture material can be formed from metal, synthetic polymer, ceramicand the like. In one example, and without limitation, the soft materialcan be formed from a hydrogel or uncrosslinked oligomers of polymerseither synthetic or of natural origin, and the like. In one aspect, thesoft material can be configured or otherwise have a means for releasingthe soft material from the stiff material. In one exemplary aspect, thereleasing means can comprise chemical degradation or other changeinitiated by light, temperature, pH, chemical catalyst, and the like.

In yet another aspect, a method of 3D cell passaging is provided thatcomprises providing a population of cells to be passaged and introducingthe population of cells into the material composition to which theyattach to at least portions of the soft material. At a desirable and orpredetermined time after the cells attachment, the method can furthercomprise causing the soft material to disassociate from the stiffmaterial, thereby releasing the soft material and the cells from thestiff material of the material composition. In another aspect, themethod can further comprise dividing the recovered cells, with orwithout remnants of the soft material, into multiple populations andrepeating the method using the subdivided populations. It is of coursecontemplated that this process can be done recursively.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate certain aspects of the instantinvention and together with the description, serve to explain, withoutlimitation, the principles of the invention. Like reference charactersused therein indicate like parts throughout the several drawings.

FIGS. 1A and 1B are views of one embodiment of the cell modules of thebioreactor system;

FIG. 2 is a schematic diagram of the embodiment of FIG. 1 followingassembly such that the two cell modules are adjacent and allowbiochemical communication between cells held in the two adjacentmodules;

FIG. 3 is one embodiment of a bioreactor system of the present inventionincluding two adjacent cell modules having independently controlled flowcharacteristics there through;

FIG. 4 is a schematic of a bioreactor system as herein disclosedincluding multiple cell culture chambers in biochemical communicationwith one another; and

FIG. 5 illustrates another embodiment of the bioreactor system in whichat least one of the cell modules of the bioreactor system can besubjected to periodic variation in hydrostatic pressure.

FIG. 6 shows Hoechst 33258 dye Day 2 and Day 5 endpoint evaluation ofcell quantity that was recovered (Cell Recovery) following digestion ofthe “soft” HA hydrogel scaffold as well as cell quantity that remained(Cell Remnant) in the scaffold after the 4 hour digestion procedure.

DETAILED DESCRIPTION OF THE INVENTION

The present invention can be understood more readily by reference to thefollowing detailed description, examples, drawings, and claims, andtheir previous and following description. However, before the presentdevices, systems, and/or methods are disclosed and described, it is tobe understood that this invention is not limited to the specificdevices, systems, and/or methods disclosed unless otherwise specified,as such can, of course, vary. It is also to be understood that theterminology used herein is for the purpose of describing particularaspects only and is not intended to be limiting.

The following description of the invention is provided as an enablingteaching of the invention in its best, currently known embodiment. Tothis end, those skilled in the relevant art will recognize andappreciate that many changes can be made to the various aspects of theinvention described herein, while still obtaining the beneficial resultsof the present invention. It will also be apparent that some of thedesired benefits of the present invention can be obtained by selectingsome of the features of the present invention without utilizing otherfeatures. Accordingly, those who work in the art will recognize thatmany modifications and adaptations to the present invention are possibleand can even be desirable in certain circumstances and are a part of thepresent invention. Thus, the following description is provided asillustrative of the principles of the present invention and not inlimitation thereof.

As used herein, the singular forms “a,” “an,” and “the” comprise pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to a “chamber” comprises aspects having two or moresuch chamber unless the context clearly indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect comprises from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance may or may not occur, andthat the description comprises instances where said event orcircumstance occurs and instances where it does not.

In simplest terms, disclosed herein are bioreactor systems. In oneaspect, the bioreactor systems disclosed herein comprise at least onecell module defining a culture chamber, an inlet, an outlet, and atleast one port opening. The cell modules of the bioreactor system can beengaged to form multi-chambered bioreactor systems. Thus, in one aspect,disclosed herein are bioreactor systems comprising at least one firstcell module defining a first cell culture chamber, an inlet, an outlet,and a port opening, wherein the port opening is on one end of the cellculture chamber and at least one second cell module defining a secondcell culture chamber, an inlet, an outlet, and a port opening, whereinthe port opening is on one end of the cell culture chamber. It isunderstood that the first and second culture chambers respectivelydefining the first and second cell modules can be separated by a barriersuch as a membrane. Thus, in another aspect, disclosed herein arebioreactor systems comprising at least one first cell module defining afirst cell culture chamber, an inlet, an outlet, and a port opening,wherein the port opening is on one end of the cell culture chamber andat least one second cell module defining a second cell culture chamber,an inlet, an outlet, and a port opening, wherein the port opening is onone end of the cell culture chamber; a membrane positioned between theopen port of said first cell module and the open port of said secondcell module.

It is further understood that the first and second cell module can bephysically engaged. Thus, in still another aspect, disclosed herein arebioreactor systems comprising at least one first cell module defining afirst cell culture chamber, an inlet, an outlet, and a port opening,wherein the port opening is on one end of the cell culture chamber andat least one second cell module defining a second cell culture chamber,an inlet, an outlet, and a port opening, wherein the port opening is onone end of the cell culture chamber; a membrane positioned between theopen port of said first cell module and the open port of said secondcell module; and wherein the first cell module and second cell moduleare sealingly engaged securing the membrane between the first and secondmodule.

The disclosed bioreactor systems can be assembled to allow for single ormultiple cultures of tissues or cells. Thus, in one aspect, thebioreactor system is directed to multi-chambered systems, such as aco-culture bioreactor system, and can, for example, be utilized for thegrowth and development of isolated cells of one or more cell types in adynamic in vitro environment more closely resembling that found in vivo.For instance, the multi-chambered bioreactor system can allowbiochemical communication between cells of different types whilemaintaining the different cell types in a physically separated state,and moreover, can do so while allowing the cell types held in any onechamber to grow and develop with a three-dimensional aspect. Inaddition, the presently disclosed bioreactor system can allow forvariation and independent control of environmental factors within theindividual chambers. For instance, it is contemplated that the chemicalmake-up of a nutrient medium that can flow through a chamber as well asthe mechanical force environment within the chamber including theperfusion flow, hydrostatic pressure, and the like, can be independentlycontrolled and maintained for each separate culture chamber of thedisclosed systems

In yet another embodiment, undifferentiated stem cells can be located ina first chamber of the bioreactor system, and one or more types offeeder cells can be located in adjacent chamber(s), which, as oneskilled in the art will appreciate, can selective be in biologicalcommunication with the first chamber. Such a bioreactor system can beutilized to, for example and without limitation, retain thedifferentiation state of cells in the first chamber and/or direct thecourse of their differentiation, as desired.

Cells and tissues used in the disclosed bioreactor systems and methodscan be obtained by any method known to those of skill in the art.Examples of sources of cells and tissues include without limitationpurchase from a reliable vendor, blood (including peripheral blood andperipheral blood mononuclear cells), tissue biopsy samples (e.g.,spleen, liver, bone marrow, thymus, lung, kidney, brain, salivaryglands, skin, lymph nodes, and intestinal tract), and specimens acquiredby pulmonary lavage (e.g., bronchoalveolar lavage (BAL)). The source ofcells and tissues obtained from blood, biopsy, or other direct ex vivomeans can be any subject having tissue or cells with the desiredcharacteristics including subject with abnormal cells or tissues whichare characteristic of a disease or condition such as, for example, acancer patient. Thus, it is contemplated herein that the subject can bea patient. It is also understood that there may be times where one ofskill in the art desires normal tissues or cells. Thus, also disclosedherein are tissues and cells obtained form a normal subject wherein a“normal” subject refers to any subject not suffering from a disease orcondition that affects the tissues or cells being obtained. It isfurther understood that the subject can comprise an organism such as amouse, rat, pig, guinea pig, cat, dog, cow, horse, monkey, chimpanzee orother nonhuman primate, and human.

Therefore, it is contemplated that exemplary cell types comprise, atleast partially and without limitation, cells having the followingexemplary morphologies: Acinar cells, Adipocytes, Alveolar cells,Ameloblasts, Annulus Fibrosus Cells, Arachnoidal cells, Astrocytes,Blastoderms, Calvarial Cells, Cancerous cells (Adenocarcinomas,Fibrosarcomas, Glioblastomas, Hepatomas, Melanomas, Myeloid Leukemias,Neuroblastomas, Osteosarcomas, Sarcomas) Cardiomyocytes, Chondrocytes,Chordoma Cells, Chromaffin Cells, Cumulus Cells, Endothelial cells,Endothelial-like cells, Ensheathing cells, Epithelial cells,Fibroblasts, Fibroblast-like cells, Germ cells, Hepatocytes, Hybridomas,Insulin producing cells, Intersticial Cells, Islets, Keratinocytes,Lymphocytic cells; Macrophages, Mast cells, Melanocytes, Meniscus Cells,Mesangial cells, Mesenchymal Precursor Cells, Monocytes, MononuclearCells, Myeloblasts, Myoblasts, Myofibroblasts, Neuronal cells, Nucleuscells, Odontoblasts, Oocytes, Osteoblasts, Osteoblast-like cells,Osteoclasts, Osteoclast precursor cells, Oval Cells, Papilla cells,Parenchymal cells, Pericytess, Peridontal Ligament Cells, Periostealcells, Platelets, Pneumocytes, Preadipocytes, Proepicardium cells, Renalcells, Salisphere cells, Schwann cells, Secretory cells, Smooth Musclecells, Sperm cells, Stellate Cells, Stem Cells, Stem Cell-like cells,Stertoli Cells, Stromal cells, Synovial cells, Synoviocytes, T Cells,Tenocytes, T-lymphoblasts, Trophoblasts, Urothelial cells, Vitreouscells, and the like; said cells originating from, for example andwithout limitation, any of the following tissues: Adipose Tissue,Adrenal gland, Amniotic fluid, Amniotic sac, Aorta, Artery (Carotid,Coronary, Pulmonary), Bile Duct, Bladder, Blood, Bone, Bone Marrow,Brain (including Cerebral Cortex), Breast, Bronchi, Cartilage, Cervix,Chorionic Villi, Colon, Conjunctiva, Connective Tissue, Cornea, DentalPulp, Duodenum, Dura Mater, Ear, Endometriotic cyst, Endometrium,Esophagus, Eye, Foreskin, Gallbladder, Ganglia, Gingiva, Head/Neck,Heart, Heart Valve, Hippocampus, Iliac, Intervertebral Disc, Joint,Jugular vein, Kidney, Knee, Lacrimal Gland, Ligament, Liver, Lung, Lymphnode, Mammary gland, Mandible, Meninges, Mesoderm, Microvasculature,Mucosa, Muscle-derived (MD), Myeloid Leukemia, Myeloma, Nasal,Nasopharyngeal, Nerve, Nucleus Pulposus, Oral Mucosa, Ovary, Pancreas,Parotid Gland, Penis, Placenta, Prostate, Renal, Respiratory Tract,Retina, Salivary Gland, Saphenous Vein, Sciatic Nerve, Skeletal Muscle,Skin, Small Intestine, Sphincter, Spine, Spleen, Stomach, Synovium,Teeth, Tendon, Testes, Thyroid, Tonsil, Trachea, Umbilical Artery,Umbilical Cord, Umbilical Cord Blood, Umbilical Cord Vein, UmbilicalCord (Wartons Jelly), Urinary tract, Uterus, Vasculature, Ventricle,Vocal folds and cells, and the like; said tissues which originate, forexample and without limitation, in any of the following species: Baboon,Buffalo, Cat, Chicken, Cow, Dog, Goat, Guinea Pig, Hamster, Horse,Human, Monkey, Mouse, Pig, Quail, Rabbit, and the like.

Referring to FIGS. 1A and 1B, a view of one embodiment of the bioreactorsystem is illustrated. In one aspect, the bioreactor system 2 comprisesat least one individual culture chamber 10, which is defined therein acell module 12. The dimensions and overall size of a cell module 12, andculture chamber 10, are not critical to the invention. In general, acell module 12 can be of a size so as to be handled and manipulated asdesired, and so as to provide access to the culture chambers eitherthrough disassembly of the device, through a suitably located accessport, or according to any other suitable method. As one skilled in theart will appreciate, the culture chamber 10 defined by the module 12 cangenerally be of any size as long as adequate for the assigned task. Inone aspect, nutrient flow can be maintained throughout athree-dimensional cellular construct growing in the culture chamber 10,so as to prevent cell death at the construct center due to lack ofnutrient supply.

Thus, in one aspect, one embodiment is a cell module 12. Though eachcell module 12 of the embodiment illustrated in FIG. 1 can comprise asingle culture chamber 10, or, optionally, a single cell module 12 cancomprise multiple culture chambers. In the latter aspect, each culturechamber of the module can comprise individual access ports (describedfurther below), so as to provide individualized flow through eachculture chamber and independent control of the local environmentalconditions in each culture chamber. While the materials from which themodule 12 can be formed can generally be any moldable or otherwiseformable material, the surface of the culture chamber 10, as well as anyother surfaces of the module that may come into contact with the cells,nutrients, growth factors, or any other fluids or biochemicals that maycontact the cells, should be of a suitable sterilizable, biocompatiblematerial. In one particular embodiment, components of the system canalso be formed so as to discourage cell anchorage at the surfaces.

It is also contemplated herein that the cell module 12 and thecomponents that make up the cell module 12 can be constructed from asingle mold rather than attaching individual pieces. That is, disclosedherein are bioreactor systems wherein each cell module comprises amonolithic construction. The advantage of such construction providesincreased sterility and removes possibilities of leaks forming. Thus, inone aspect, the cell module 12 can be constructed of any materialsuitable to being formed in a mold.

In one embodiment two cell modules 12 can be selectively coupled via acompression fitting so form two culture chambers 10 that are adjoinedand are in selective biological communication with each other. Thus, inone aspect, the cell modules 12 can comprise a means for sealinglyengaging the top surface of one module with the top surface of anothermodule. It is understood that once fully engaged, the two cell modulescan selectively, and optionally releasably, lock into place. In oneaspect, it is contemplated that the means for sealingly engaging therespective cell modules will cause a compressive force to be effected onthe adjoined surfaces of the respective modules. It is understood thatthere are many means for sealingly engaging two cell modules 12. Onesuch method is shown in FIG. 1A. In this aspect, a male compressionfitting 35 can be configured to sealingly engage the fitting 36 to forma compression fitting. In one aspect, the fitting 36 can have a raisedportion and the male compression fitting 35 an indentation that whenaligned form a lock. It is understood that such an engagement meanscould be engaged using a press and twisting motion. It is furtherunderstood that said engagement means could be disengaged by twisting inthe opposite direction. It is further understood that the cell module 12comprises both the male compression fitting 35 and female fittings 36 onthe same or opposing faces of the cell module 12. For example, the cellmodule 12 can comprise male compression fittings on one face and femalefittings 36 on the opposite face. Alternatively, the cell module 12 cancomprise male compression fittings 35 and female fittings 36 on the sameface. It is understood that the placement of the male fittings 35 andfemale fittings 36 is such that compression and stability are maximized,for example, with male compression fittings 35 being at opposite cornersor sides from each other but adjacent to female fittings 36 which are onopposite sides or corners from each other.

Alternatively, the two cell module system can comprise a first cellmodule 12 and a second cell module 12, wherein the first and secondmodule comprise identical cell chambers 10, inlets, and outlets, butwherein the first cell module 12 comprises one or more male compressionfittings and the second cell module 12 comprises one or more femalefittings. For example, the first cell module 12 can comprise only malecompression fittings 35 and the second cell module 12 can comprise onlyfemale fittings 36. In an alternative example, the top surface of thefirst cell module 12 can comprise a raised perimeter with a convex bevellocated at the mid point to three fourths point on the interior wall ofthe raised perimeter. The top surface of the second cell module 12 canhave a perimeter relief that is of a depth to receive the male fittingon the first cell module. Additionally, the relief on the second cellmodule 12 can have a concave indentation which can form a lock when theconvex bevel of the first cell module 12 is engaged. Similarly, thefirst and second cell modules 12 can be threaded in such a manner toallow the first module to be screwed down on the second module.

Thus, in one aspect a cell culture system can comprise first and secondcell modules 12 capable of engaging wherein the first and second cellmodule are identical and interchangeable. In another aspect, the cellculture system can comprise a first and second cell module 12, whereinthe first and second cell module are not identical or interchangeablebut capable of being engaged.

It is further contemplated that the cell culture systems disclosedherein can comprise one or more first and second cell modules. The cellculture systems can have cell modules 12 independently controlled orserially linked through the outlet of one first and second cell moduleto the inlet of a second first and second cell module. The connectionsof inlets and outlets to media source, reagents, or flow source can beregulated by valves or linked directly to said source. Alternativelywhen serial linking is used, the outlet of one cell module 12 can bedirectly linked to the inlet of a second cell module 12 or have acontrolled connection such as with a valve.

The culture chamber 10 can generally be of a shape and size so as tocultivate living cells within the chamber. In one preferred embodiment,culture chamber 10 can be designed to accommodate a biomaterial scaffoldwithin the culture chamber 10, while ensuring adequate nutrient flowthroughout a cellular construct held in the culture chamber 10. Forinstance, a culture chamber 10 can be between about 3 mm and about 10 mmin any cross sectional direction. In another embodiment, the culturechamber can be greater than about 5 mm in any cross sectional direction.For instance, the chamber can be cylindrical in shape and about 6.5 mmin both cross sectional diameter and height. The shape of culturechamber 10 is not critical to the invention, as long as flow can bemaintained throughout a cellular construct held in the chamber.

It is understood that the formation of the culture chamber creates avolumetric reservoir or a size determined by the cross sectionaldirection and depth of the chamber. Accordingly, it is understood thatthe disclosed culture chambers 10 can be between 1 μL and 50 mL, 50 μLand 1 mL, 100 μL, and 500 μL, or 250 μL or any volume therebetween.Typically the culture chamber is circular or oval in cross sectionalshape. However, it is further understood that the cross sectional shapeof the culture chamber 10 can also be hexagonal, heptagonal, octagonal,nonagonal, decagonal, hendecagonal, dodecagonal, or larger polygon inshape. Additionally, it is contemplated herein that the closed end of acell culture chamber 10 can be flat or convex. It is understood thatfewer angles and abrupt changes in plane encourages cells to avoidadhering to the walls of the culture chamber and reduce turbulence offluids passing through the chamber. Thus, it is contemplated herein thatthe shape of the culture chamber can be selected based on the particularcharacteristics one of skill in the art desires to replicate.

In one aspect, the culture chamber 10 is defined by an open end port onthe top surface of the cell module 12 and a closed end on the bottomsurface of cell module 12. The open end allows for the addition for cellanchorage and cells and can be sealed by a membrane 23 (see FIG. 2). Itis also contemplated that the culture chamber can be open at both endsand, in this aspect, the open ends of the culture chamber 10 are definedin the respective top and bottom surfaces of the cell module 12. Inanother aspect the culture chamber 10 is defined by an opened end porton both the top and bottom surface. As one skilled in the art willappreciate, when the culture chamber 10 is defined by two opened ports,the open ended ports can be closed by mating the cell module 12 with asecond cell module 12 and placing a membrane between the respective cellculture chambers 10. Thus, in another aspect, disclosed herein arebioreactor systems further comprising at least one third cell module,wherein the third cell module comprises a cell chamber open at bothends, wherein the cell chamber of the third cell module is closed bysealingly engaging the first and second cell modules on opposite facesof the third cell module 12.

In another aspect, the system can comprise a material composition. Forexample, it is contemplated that the material composition can beconfigured to serve as a cell anchorage that can be contained in theculture chamber 10. The term “cell anchorage” as utilized herein refersto one or more articles upon which cells can attach and develop. Forinstance, the term “cell anchorage” can refer to a single continuousscaffold, multiple discrete scaffolds, or a combination thereof. Theterms “cell anchorage,” “cellular anchorage,” and “anchorage” areintended to be synonymous. It is contemplated that any suitable cellanchorage as is generally known in the art can be located in the culturechamber 10 to provide anchorage sites for cells and to encourage thedevelopment of a three-dimensional cellular construct within the culturechamber 10.

For purposes of the present disclosure, the term continuous scaffold isherein defined to refer to a construct suitable for use as a cellularanchorage that can be utilized alone as a single, three-dimensionalentity. A continuous scaffold is usually porous in nature and has asemi-fixed shape. Continuous scaffolds are well known in the art and canbe formed of many materials, e.g., coral, collagen, calcium phosphates,synthetic polymers, and the like, and are usually pre-formed to aspecific shape designed for the location in which they will be placed.Continuous scaffolds are usually seeded with the desired cells throughabsorption and cellular migration, often coupled with application ofpressure through simple stirring, pulsatile perfusion methods orapplication of centrifugal force.

Discrete scaffolds are smaller entities, such as beads, rods, tubes,fragments, or the like, for example tubes for the formation of vasculartubes. When utilized as a cellular anchorage, a plurality of identicalor a mixture of different discrete scaffolds can be loaded with cellsand/or other agents and located within a void where the plurality ofentities can function as a single cellular anchorage device. Exemplarydiscrete scaffolds suitable for use in the present invention that havebeen found particularly suitable for use in vivo are described in U.S.Pat. No. 6,991,652, which is incorporated herein in it's entirety byreference. A cellular anchorage formed of a plurality of discretescaffolds can be preferred in certain embodiments of the bioreactorsystem as discrete scaffolds can facilitate uniform cell distributionthroughout the anchorage and can also allow good flow characteristicsthroughout the anchorage as well as encouraging the development of athree-dimensional cellular construct.

In one embodiment, for instance when considering a cellular anchorageincluding multiple discrete scaffolds, the anchorage can be seeded withcells following assembly and sterilization of the system. For example,an anchorage including multiple discrete scaffolds can be seeded in oneoperation or several sequential operations. Optionally, the anchoragecan be pre-seeded, prior to assembly of the system. In one aspect, theanchorage can comprise a combination of both pre-seeded discretescaffolds and discrete scaffolds that have not been seeded with cellsprior to assembly of the bioreactor system.

The good flow characteristics possible throughout a plurality ofdiscrete scaffolds can also provide for good transport of nutrients toand waste from the developing cells, and thus can encourage not onlyhealthy growth and development of the individual cells throughout theanchorage, but can also encourage development of a unifiedthree-dimensional cellular construct within the culture chamber. Thus,it is understood the scaffolds and matrices utilized herein can compriseshapes akin to real tissues with meaningful volumes.

The materials that are used in forming an anchorage can generally be anysuitable biocompatible material. In one embodiment, the materialsforming a cellular anchorage can be biodegradable. For instance, acellular anchorage can comprise biodegradable synthetic polymericscaffold materials such as, for example and without limitation,polylactide, chondroitin sulfate (a proteoglycan component), polyesters,polyethylene glycols, polycarbonates, polyvinyl alcohols,polyacrylamides, polyamides, polyacrylates, polyesters, polyetheresters,polymethacrylates, polyurethanes, polycaprolactone, polyphophazenes,polyorthoesters, polyglycolide, copolymers of lysine and lactic acid,copolymers of lysine-RGD and lactic acid, and the like, and copolymersof the same. Optionally, an anchorage can comprise naturally derivedbiodegradable materials including, but not limited to, chitosan,agarose, alginate, collagen, hyaluronic acid, and carrageenan (acarboxylated seaweed polysaccharide), demineralized bone matrix, and thelike, and copolymers of the same.

It is contemplated that exemplary scaffold materials can comprise, atleast partially and without limitation: Collagen; PLA/poly(lactide);PLGA/poly(lactic-co-glycolic acid;) Chitosan; PCL/poly(e-caprolactone);Alginate/sodium alginate; PGA/poly(glycolide); Hydroxyapatite; Gelatin;Matrigel™; Fibrin; Acellular/Allogenic Tissue (all forms); HyaluronicAcid; PEG/poly(ethylene glycol); Peptide; Silk Fibroin; Agarose/Agar;Calcium phosphate; PU/polyurethane; TCP/tri calcium phosphate;Fibronectin; PET/poly(ethylene terephthalate); Bioglass; PVA/Polyvinylalcohol; Laminin; GAG/glycosaminoglycan; Cellulose; Titanium;DBP/demineralized bone powder; Silicone; PEGDA/PEG-diacrylate;Fibrinogen; Acellular/Allogenic Tissue-SIS; PDMS/polydimethylsiloxane;Acellular/Allogenic Tissue-Bone; ECM (in situ derived); Polyester;Elastin; PS/polystyrene; Glass; PBT/polybutylene terephthalate; Dextran;PEG/poly(ethylene glycol)-other modified forms; PES/polyethersulfone;PLL/poly-l-lysine; MWCNT/multiwalled carbon nanotube;PRBV/poly(hydroxybutyrate-co-hydroxyvalerate); Coral; Starch;PPF/poly(propylene fumarate); PLCL/poly(lactide-co-e-caprolactone);Chondroitin Sulfate; PAM/polyacrylamide; PC/polycarbonate;PEUU/poly(ester urethane)urea; Calcium carbonate; Atelocollagen;PHB/poly(hydroxybutyrate); Polyglactin; Gelfoam®; Acellular/AllogenicTissue-Vasculature; PuraMatrix™; PAA/poly(acrylic acid); PA/polyamide(Nylon); Clot; PDO/polydioxanone; PMMA/poly(methyl methacrylate)(acrylic); Acellular/Allogenic Tissue-Heart Valve;PHEMA/poly(hydroxyethyl methacrylate); PVF/polyvinyl formal;PGS/poly(glycerol sebacate); PEO/poly(ethylene oxide);Acellular/Allogenic Tissue-Cartilage; Pluronic® F-127;PHBHHx/PHB-co-hydroxyhexanoate; PHP/polyHIPE polymer; Polyphosphazene;Silicate; Poly-D-lysine; Poly peptide/MAXI; Aluminum oxide;PTFE/polytetrafluoroethylene; Silica/silicon dioxide;SWCNT/single-walled carbon nanotube; Cytomatrix® (Tantalum);PLG/poly(L-lactide-glycolide); ORMOCER®; POSS/polyhedral oligomericsilsesquioxanes; Acellular/Allogenic Tissue-Tendon; HEWL/Hen egg whitelysozyme; Polyelectrolyte; Polyamidoamine; POC/poly(octanediol citrate);PEI/polyethyleneimine; Hyaff-11®; PTMC/poly(trimethylene carbonate);PAAm/Poly(allylamine); Polyester utethane; Lactose;PNiPAAm/poly(N-isopropylacrylamide); Polyurethane-urea; Keratin; CyclicAcetal; NiPAAm; Poly HEMA-co-AEMA; PE/polyethylene (all forms);PLDLA/poly(L/D)lactide; Vitronectin; PDL/poly-D-lysine; Corn starch;TMP/trimethylolpropane; Poloxamine; Acellular/Allogenic Tissue-Skin;Gellan gum; PEMA/poly(ethyl methacrylate); Tantalum; DegraPol®;Silastic; Akermanite; Polyhydroxyalkanoate; AlloDerm®; Polyanhydrides;Zirconium Oxide; Polyether; TMC/trimethylene carbonate; Sucrose;PEVA/poly(ethylene-vinyl alcohol); PMAA/poly(methacrylic acid);Hydrazides; Poly(diol citrate); PVDF/polyvinylidene fluoride;COBB/Ceramic Bovine Bone; PVLA/polyvinylbenzyl-D-lactoamide;PCU/poly(carbonate-urea)urethane; MBV; Chitin; Synthetic elastin;PBSu-DCH/diisocyanatohexane-extended poly(butyl); PANI/polyaniline;Polyprenol; Zein; Egg Shell Protein; EVA/Ethylene Vinyl Acetate;Gliadin; HPMC/hydroxypropyl methylcellulose; PE/phthalate ester;Thrombin; PP/Polypropylene; OptiCell™; PEEP/poly(ethyl ethylenephosphate); OCP/Octacalcium Phosphate; PEA/poly(ester amide); Aggrecan;Graphite; NovoSorb™; PLO/poly-L-ornithine; DOPE/dioleoylphosphatidylethanolamine; ELP/Elastin-like polypeptide; LDI/lysinediisocyanate; PPC/poly (propylene carbonate); Plasma; Fe(CO)(5)/Ironpentacarbonyl; Asbestos; PPE/polyphosphoester; Azoamide; Triacrylate;PRP/platelet-rich plasma; Dextran (modified forms);PGSA/poly(glycerol-co-sebacate)-acrylate; Polyorthoester; SPLE/sodiumpolyoxyethylene lauryl ether sulfate; Methacryloyloxy; TGA/thioglycolicacid; PCTC/poly(caprolactone-co-trimethylene carbonate; SU-8; SLG/sodiumN-lauroyl-L-glutaminate; Polysulfone; Phosphophoryn; HEA/hydroxyethylacrylate; PSSNa/poly(sodium styrene sulfonate); Carbon Foam;PFOB/perfluorooctyl bromide; Lecithin; Mebiol®; BHA/butylatedhydorxyanisole; Surgisis®; OsSatura™; Skelite™; Cytodex™; COLLOSS®; E;Magnesium; PAN/polyacrylonitrile; HPMA/hydroxypropyl-methacrylamide;Lutrol® F127; PDTEc/poly(desaminotyrosyl-tyrosineethyl esterc; Rayon(commercial product); Organo Clay; Portland Cement; Xyloglucan; VateriteComposites (SPV); PRx/polyrotaxane; AW-AC/anti-washout apatite cement;Starch acetate; Nicotinamide; POR/poly-L-ornithine hydrobromide;AM-co-VPA/acrylamide-co-vinyl phosphonic acid; Calcium Silicate;Carbylan GSX; Colchicine; GPTMS/glycidoxypropyltrimethoxysilane;Phosphorylcholine; PLE/polyoxyethylene lauryl ether; Tartaric acid;HPA/hydroxyphenylpropionic acid;PLVA/poly-N-p-vinylbenzyl-D-lactonamide;PEOT/polyethyle-neoxide-terephtalate; Adipose Tissue Powder; SLS/sodiumlauryl sulfate; KLD-12 peptide; PDTOc/poly(desaminotyrosyl-tyrosineoctylesterc; Si-TCP/silicate-substituted tricalcium phosphate;PCLF/polycaprolactone fumarate;PAMPS/poly(acrylamidomethylpropanesulfonicsodiu; Bio-Oss®; MGL/monoglyceryl laurate; DMA/fullerene C-60 dimalonic acid;THF/tetrahydrofuran; Polyphosphoester; Paper; Calcium-silicon;PPD/poly-p-dioxanone; BME/Basement Membrane Extract (generic); andOPF/oligo[poly(ethylene glycol)fumarate].

A biodegradable anchorage can comprise factors that can be released asthe scaffold(s) degrade. For example, an anchorage can comprise withinor on a scaffold one or more factors that can trigger cellular events.According to this aspect, as the scaffold(s) forming the cellularanchorage degrades, the factors can be released to interact with thecells. Referring again to FIGS. 1A and 1B, in those embodimentsincluding a cellular anchorage formed with a plurality of discretescaffolds, a retaining mesh 14 can also be located within the culturechamber 10. The retaining mesh 14 can be formed of any suitablebiocompatible material, such as polypropylene, for example, and can lineat least a portion of a culture chamber 10, so as to prevent materialloss during media perfusion of the culture chamber 10. Alternatively,the retaining mesh can be a located at the opening of the inlet andoutlet of the culture chamber 10. The retaining mesh 14 can be anintegral part of the inlet and outlet so as to be made of the samematerial and in the same form as the cell module 12 such that theretaining mesh 14 is not removable for the cell module 12. A porousretaining mesh 14 can generally have a porosity of a size so as toprevent the loss of individual discrete scaffolds within the culturechamber 10. For example, a retaining mesh 14 can have an average poresize of between about 10 μm and about 1 mm, between about 50 μm andabout 700 μm, or between about 150 μm and about 500 μm.

Upon assembly of the bioreactor system, two (or more) culture chambers10 can be aligned so as to be immediately adjacent to one another. Inone aspect, to help create a fluid-proof seal of the system, a gasket 16and a permeable membrane portion 23 can be positioned between theadjoining surfaces of the cell modules to selectively prevent fluidleakage from between the respective open ends (the respective ports ofthe culture chambers). In one aspect, the gasket 16 and the membraneportion 23 can be formed as a single integrated structure. It iscontemplated that the membrane portion 23 of gasket 16 can be positionedbetween the respective ports adjoined culture chambers 10 and can have aporosity that can allow biochemical materials, for instance growthfactors produced by a cell in one chamber, to pass through the membraneand into the adjoining chamber, where interaction can occur between thebiochemical material produced in the first chamber and the cellscontained in the second chamber.

Optionally, the two or more culture chambers 10 can be aligned with onlythe membrane portion 23 positioned between the adjoining surfaces of thecell modules and in over/underlying relationship to the respective portsof the adjoining chambers. In operation, by interlocking two cellmodules 12, the membrane portion 23 can be compressed therebetween theadjoining surface to effect a fluid-proof seal around the ports of theculture chamber 10. Thus, in this exemplary aspect, the membrane acts asa gasket. In a further alternative embodiment, at least one of the cellmodules can comprise a raised convex concentric ring which encircles theopen end, the port, of the culture chamber 10 on the top surface of thecell module 12. In this aspect, when the two cell modules areinterlocked the added pressure placed on the raised area effects a sealon the membrane that is interposed therebetween. In a further aspect,the cell modules can comprise a male and female cell module where themale module comprises a raised convex concentric ring which encirclesthe open end, the port, of the culture chamber 10 on the top surface ofthe cell module 12 and the female cell module comprises a concaveconcentric ring which encircles the culture chamber 10 on the topsurface of the female cell module 12. When the male and female cellmodules are engaged, the male and female rings form a bight in themembrane creating a seal and aid in alignment of the culture chambers12.

In bioreactor systems where a membrane is used without a gasket, themembrane becomes a gasket by compressing the membrane under thecompression formed by the interlocking of two or more cell modules 12.Therefore, it is understood and herein contemplated that the membranecan comprise a compressible material that is conducive to the formationof a gasket. Such materials are well known to those of skill in the art.

In various aspects, it is contemplated that the membrane 23 can be asolid, non-porous, or semi-permeable (i.e., porous) membrane. Theporosity can be small enough to prevent passage of the cells or cellextensions from one chamber to another. In particular, the membraneporosity can be predetermined so as to discourage physical contactbetween the cells held in adjacent chambers, and thus maintain isolationof the cell types. Suitable porosity for a membrane can be determinedbased upon specific characteristics of the system, for instance thenature of the cells to be cultured within the chamber(s). Suchdetermination is well within the ability of one of ordinary skill in theart and thus is not discussed at length herein.

Additionally, the membrane 23 can comprise not only material thataffects the transmission of physical parameters, but opticaltransmission as well. Thus, contemplated herein are membranes 23 whereinthe membrane only allows the transmission of certain wavelengths oflight to pass from one side of the membrane to the other or excludesspecific wavelengths of light.

Alternatively, the membrane 23 can comprise a composite structure ofboth porous and non-porous or solid membranes, which allow the removalof one non-porous membrane while the other porous membrane remains inplace between the culture chambers 10. In one aspect, the non-porous orsolid membrane can be affixed to the porous membranes and separated fromthe porous membrane without needing to remove the semi-permeablemembrane. Thus, the solid membrane allows for separate culturingconditions and media usage; whereas a porous membrane allows for thepassage of biochemical materials. In another aspect, the membrane 23comprising a porous and solid or nonporous membrane can be placedbetween adjoined culture chambers to allow for separate cultureconditions and after a period of time the solid or non-porous membranecan be removed to allow for passage of biochemical materials.

In another alternative, the membrane 23 can comprise a biodegradablematerial. Through the use of a biodegradable material for the membrane23, porosity can be electively increased over the course of the usage ofthe membrane. For example, a non-porous membrane 23 made ofbiodegradable material can be used which prevents the exchange ofculture conditions. In operation, as the material is used, the membranedegrades allowing for the exchange of biochemical materials. In afurther alternative, the membrane 23 can comprise biodegradable andnon-biodegradable material such as a porous non-biodegradable membranewhere the pores are sealed with a biodegradable material or coating. Asthe biodegradable material or coating is dissolved, the non-degradableporous membrane is revealed.

In another embodiment the cells contained in a culture chamber 10 can bemaintained at a distance from the membrane 23 to discourage physicalcontact between cells held in adjacent culture chambers. For instance,in this example, retaining mesh 14 can be located between a cellanchorage held in a culture chamber and the membrane located between twoadjacent chambers. The width of the retaining mesh 14 can preventcontact of the cells with the membrane 23. Optionally, the retainingmesh 14 can be at a distance from the membrane 23, providing additionalseparation between the membrane 23 and cells held in the culture chamber10. In another embodiment, a continuous scaffold can be located in aculture chamber 10 at a distance from the membrane 23 so as todiscourage physical contact between the cells held in the culturechamber and the membrane 23. While a preferred distance between themembrane 23 and cells held in the chamber will vary depending upon thespecific characteristics of the system as well as the cells to becultured in the system, in general, the distance between the two can beat least about 100 microns.

Each culture chamber 10 of the system can comprise, the capability forindependent flow control through the chamber. For example, and referringagain to FIGS. 1A and 1B, each individual culture chamber 10 cancomprise an inlet 8 and an outlet 9 through which medium can flow. Inthis exemplary aspect, the inlet 8 and outlet 9 can be connected tomedium perfusion tubing via quick-disconnect luers 18 and stopcockvalves, but this particular arrangement is not a requirement of theinvention, and any suitable connection and perfusion system as isgenerally known in the art can be utilized. In another embodiment, theconnection can be an integral portion of a single formed module 12. Forexample, the luers 18 can be formed at the outward ends of the inlet 8and outlet 9 as shown in FIG. 1. It is understood and hereincontemplated that other means for attaching tubing and stopcock valvesare well known in the art and can be used in the present invention as analternative to a luer lock. Such attachment mechanisms comprise but arenot limited to compression fittings, threaded fittings, and friction.

It is contemplated that at least portions of the respective inlet 8 andoutlet 9 can be straight or can comprise one or more bends. It isunderstood that the inlet 8 and outlet 9 do not have to line up withinthe culture chamber 10, but can be situated at opposing ends (i.e., oneat the top and another the bottom as reflected in the middle module inFIG. 4). It is contemplated that the respective shapes of the inlet andoutlet can be configured to affect the desired flow characteristicswithin the chamber.

Referring to FIG. 2, one aspect of a pair of adjoined modules 12following assembly is shown. As can be seen, the embodiment comprisestwo modules 12, each of which comprises a single culture chamber 10.Upon assembly, the two culture chambers 10 are aligned with thepermeable membrane portion 23 of gasket 16 positioned therebetween theports of the culture chambers. In this particular embodiment, aplurality of discrete scaffolds 15 has been located within each of thetwo culture chambers 10 as a cellular anchorage. In addition, eachculture chamber 10 can be lined with a retaining mesh 14, as shown. Uponassembly, desired media can be independently perfused through eachculture chamber 10 via the separate inlets 8 and outlets 9.

FIG. 3 illustrates one embodiment of a bioreactor system according tothe present invention. This aspect comprises two assembled modules 12,such as those illustrated in FIG. 2, each in line in a flow circuit thatis completely independent of the other that includes a pump 17, forinstance a peristaltic pump and a media container 19. In this aspect,gas exchange can be facilitated by two methods, including a first methodutilizing a coiled length of a gas permeable tubing 18 such as, forexample, a platinum-cured silicone tubing, as well as a second methodincluding an air filter 22 located, in this aspect, at the mediacontainer 19. Any gas exchange method as is known can alternatively beutilized, however.

One skilled in the art will appreciate that one of the many benefits ofthe disclosed invention is the versatility of the system and cellmodules. For example, in the bioreactor system illustrated in FIG. 3,the design attributes allow convenient and flexible reversal of theperfusion flow for a particular experimental protocol.

The bioreactor systems are not limited to single culture bioreactorsystems or co-culture bioreactor systems in which only two independentlycontrolled culture chambers are located adjacent to one another. Inother aspects, additional cell modules can be selectively added to thebioreactor system such that a single culture chamber can be in selectivebiochemical communication with the contents of two or more other culturechambers. For example, a third chamber can house cells that can be inbiochemical communication with the first culture chamber, optionallywith a membrane separating the first and third chambers, though thisaspect is not a requirement of the system such as for example in theinstance stacked arrangement as illustrated in FIG. 4.

In one aspect, it is contemplated that the number of additional thirdchambers, which can be interior cell modules 12, which can be employedis not limited to a single interior cell module (i.e., three total cellmodules 12 (one interior cell module and two end cell modules)), but cancomprise 2, 3, 4, 5, 6, 7, 8, 9, 10 or more interior cell modules (i.e.,4, 5, 6, 7, 8, 9, 10, 11, 12, or more total cell modules 12,respectively). Thus, as a further embodiment disclosed herein are cellmodules 12 that can be utilized as interior cell modules in a stackedconfiguration. Such interior cell modules 12 can comprise two topsurfaces. Because the interior cell modules 12 comprise two topsurfaces, the culture chamber 10 of these modules is open at both endsto allow for biochemical passage between the interior module and each ofthe exterior modules. As with the exterior cell modules, the top surfaceof the interior cell modules 12 can comprise means of sealingly engagingthe top surface of other cell modules 12. Thus, it is contemplatedherein that both of the top surfaces of the interior module 12 cancomprise female fittings, male compression fittings, or a combination ofboth on each surface. Moreover, it is understood that the top surfacesof the interior cell module 12 can be identical or comprise anorientation with a male and a female end.

In another embodiment, one or more of the culture chambers of the systemcan be designed so as to provide the capability of subjecting theinterior of the culture chamber to variable dynamic mechanical stimulisuch as mechanical loading or variation in fluid flow through theculture chamber in order to vary the associated stress on the developingcells. Additionally one or more culture chambers of the system can bedesigned as to provide the capability of subjecting the interior of theculture chamber to electric current or a light source. Such anembodiment can be utilized to, for instance, trigger differentiation anddevelopment of stem cells contained in a culture chamber. In addition,cyclical hydrostatic loading patterns can be established, if desired, bysimply cycling the pressurized fluid through the pressure chamber 24through use of a solenoid valve and a time-delay relay, computerautomation, or any other method that is generally known to one ofordinary skill in the art. Also, electrical currents can be providedthrough the use of an electrical probe in culture chamber of an adjacentcell module 12.

For example, according to one aspect, as illustrated in FIG. 5, a cellmodule 12 can be located immediately adjacent to a second cell module(not shown in FIG. 5), as described above. In addition, the cell module12 can, on a second side of the module 12, be aligned with a pressuremodule 32 that can be utilized to vary the hydrostatic pressure on thecontents of the culture chamber 10. According to this embodiment, theculture chamber 10 can be aligned with a pressure chamber 24 defined bypressure module 32, and the two adjacent chambers 10, 24 can beseparated by an impermeable diaphragm 26. The introduction ofpressurized fluid, e.g., air, into the pressure chamber 24, can deflectthe diaphragm 26, as shown in FIG. 5B, and transfer the pressure to thevolume of fluid in the culture chamber 10. In one embodiment, fluid flowthrough the culture chamber 10, as well as through other adjacentculture chambers, can be stopped prior to pressurizing the system, so asto develop a fixed volume of fluid within the affected portion of thesystem.

In another embodiment, each cell module can be designed to allow for thedirect sampling and observation of the culture chamber such as opticaland spectrophotometric analysis. Such designs can comprise but are notlimited to optically transmissive culture chamber 10 such that thebottom of the well of the culture chamber comprises optical glass orplastic (i.e., a cell module comprising optically transmissiblematerial). Thus, a microscope can directly visualize the culture chamber10 by focusing through the optically transmissive culture chamber on thebottom side of the cell module 12. Additionally, high resolution andthree-dimensional imaging modalities including, but not limited to,laser confocal microscopy, multiphoton microscopy, optical coherencetomography, and nuclear magnetic resonance can be used to visualize thecell culture. The cell module 12 can be made from opaque material, forexample and without limitation, the cell module can be made from opaquewhite material for luminescent detection or opaque black material forfluorescent detection to effectively limit endogenous background signal.Additionally, the cell module 12 can comprise translucent,photoreactive, or optically filtering glass or polymers. For example,the cell module 12 can comprise a polymer that allows the passage ofcertain wavelengths of light or filters out ultraviolet light.Similarly, the culture chambers can comprise an inlet through which ananalytical probe may be inserted.

It is understood that when sampling an observation of culture chamber isundertaken, it can be useful to provide a mechanism for securing thecell module 12 on any device used for observation such as a microscopeor plate reader such as a spectrometer. Thus, disclosed herein are cellmodules mounted in a microscope stage adaptor. Also disclosed are cellmodules 12 mounted to well plate adaptor for use in instrumentation,i.e., spectrometer plate reader.

In yet another embodiment, an electrical current can be provided to theinterior of a culture chamber 10 through the use of a piezoelectricmembrane 23. The piezoelectric membrane upon compression generates anelectric current which is supplied to the culture chamber. In analternative aspect, the electric current can be supplied through the useof cell anchorage constructed with a piezoelectric material. Forexample, as pressure is applied through the introduction of apressurized fluid, an electrical current is emitted from the cellanchorage. Alternatively, the bioreactor systems disclosed herein cancomprise an electrically charging or piezoelectric scaffold.

In various aspects, multiple independent bioreactor systems can beprovided that can incorporate various combinations of experimentalstimuli, which can provide real time comparisons of the differingstimuli on the developing cellular constructs.

In a further aspect, a bank of multiple and identical systems can beestablished that can provide replication of a single experimentalprocedure and/or to provide larger cumulative amounts of the productcells that are grown, developed or otherwise produced within each of theindividual culture chambers.

It is contemplated that the disclosed culture systems can beincorporated into a singular instrument to allow for the control oftemperature, gas exchange, media contents and flow rate, external andmechanical stresses, and endpoint analysis. The instrumentation cancomprise multiple modular components each designed to accomplish aspecific task. Thus, for example, the disclosed instrumentation cancomprise one or more of a means for seeding cells onto anchorages, ameans for controlling the flow of media, a means for adding or changingmedia, a means for subjecting the culture to mechanical stress orpressure, an analytical probe, and a device for manipulating theparameters of the various modules as well as collecting and analyzingdata (for example, a computer and a computer program designed toaccomplish these tasks).

The culture systems disclosed herein have many uses known to those ofskill in the art. For example, the disclosed culture systems and cellmodules can be used in tissue engineering where a 3D bioreactor isuseful to properly model tissue.

In a further aspect, it is contemplated that for tissue passaging, amaterial composition comprising two or more materials can be used. Inone example, the material composition can comprise a stiff culturematerial having substantially large porosity, such as, for example andwithout limitation, having pores of average size between 50 μm and 2 mm,into which a soft culture material has been introduced. “Stiff culturematerial” is defined herein as tissue culture material having a tensileelastic modulus, or Young's modulus, of about 1 GPa or greater and “softculture material is defined as tissue culture material having a tensileelastic modulus, or Young's modulus, of about 500 MPa or less. In oneexample, and without limitation, the stiff culture material can beformed from metal, synthetic polymer, ceramic and the like. In oneexample, and without limitation, the soft culture material can be formedfrom a polymer of biological origin, a synthetic polymer, or acombination of biological and synthetic polymers. The soft culturematerial may then be formed as a hydrogel or an uncrosslinked oligomersof polymers either synthetic or of natural origin, and the like.

It is understood that as the bioreactor systems disclosed herein areutilized for passaging cells in culture, that in one aspect, thedisclosed bioreactor systems comprise cells. It is further understoodthat the cells attach to the culture material. Thus, in one aspect,disclosed herein are bioreactor systems further comprising cellsattached to the culture material. In one aspect, the cells are attachedto the soft culture material. The cells can be introduced to the softculture material before or after introduction of the soft culturematerial to the stiff culture material. Thus, in one aspect, the cellsare introduced to the soft culture material and with the soft culturematerial introduced to the stiff culture material. For example, thecells can be encapsulated in a hydrogel soft culture material and thenintroduced to the stiff culture material.

In one aspect, the soft culture material can be configured or otherwisehave a means for releasing the soft material from the stiff culturematerial. In one exemplary aspect, the releasing means can comprisechemical degradation or other change initiated by light, temperature,pH, chemical catalyst, and the like.

In another aspect, the material composition may further comprise abiocompatible aqueous solvent such as, for example and withoutlimitation, Minimum Essential Medium (MEM), developed by Harry Eagle,and its many altered forms. In this aspect, it is contemplated that thebiocompatible aqueous solvent can provide the basic benefits of cellculture media, which include, without limitation, provision of nutrientsand removal of cell waste.

Further, in addition to the usual or conventional soluble factors knownto be generally beneficial for the sustained culture of cells, such as,for example and without limitation, Inorganic Salts: CaCl2 (anhydrous),Fe(NO3)3.9H2O, MgSO4 (anhydrous), KCl, NaHCO3, NaCl, NaH2PO4.H2O; AminoAcids: L-Alanine, L-Arginine.HCl, L-Asparagine.H2O, L-Aspartic Acid,L-Cysteine.HCl, L-Cystine.2HCl, L-Glutamic Acid, L-Glutamine, Glycine,L-Histidine.HCl.H2O, L-Isoleucine, L-Leucine, L-Lysine.HCl,L-Methionine, L-Phenylalanine, L-Proline, L-Serine, L-Threonine,L-Tryptophan, L-Tyrosine.2Na.2H2O, L-Valine; Vitamins: L-AscorbicAcid.Na, D-Biotin, Choline Chloride, Folic Acid, myo-Inositol, LipoicAcid, Nicotinamide, D-Pantothenic Acid, (hemicalcium), Pyridoxine.HCl,Riboflavin, Thiamine.HCl; Other: Adenosine, Cytidine, 2′-Deoxyadenosine,2′-Deoxycytidine.HCl, 2′-Deoxyguanosine, D-Glucose, Glutathione(reduced), HEPES, Phenol Red (Sodium Salt), Pyruvic Acid, SodiumPyruvate, Thioctic Acid, Thymidine, Uridine, and the like, the aqueoussolvent can provide specific soluble factors and/or stimulants which areknown to affect, e.g., either increase, decrease or stabilize, cellproliferation within the exemplary stiff/soft material composition. Inanother aspect, the aqueous solvent may comprise oligomers or fragmentsof the soft material that are known to effect cell attachment to thesoft material originally contained within the stiff culture material,such as, for example and without limitation, natural materials common tomammalian tissue such as collagen, chondroitin sulfate, fibrin,fibrinogen, glycosaminoglycan, hyaluronic acid, keratin, laminin, orthrombin; natural materials common to non-mammalian tissue or derivedfrom non-mammalian organisms such as chitin, chitosan, dextran, starchesor other polysaccharides, gelatin, silks, or synthetic materials such asHEMA/hydroxyethyl methacrylate, PCL/poly(e-caprolactone),PEG/poly(ethylene glycol), PEMA/poly(ethyl methacrylate),PEO/poly(ethylene oxide), PEVA/poly(ethylene-vinyl alcohol),PGA/poly(glycolide), PHEMA/poly(hydroxyethyl methacrylate),PLA/poly(lactide), PLG/poly(L-lactide-glycolide),PLGA/poly(lactic-co-glycolic acid), PLL/poly-l-lysine,PLLA/poly(L-lactic acid), PVA/Polyvinyl alcohol and the like.

Optionally, the material composition can comprise a stiff tissue culturematerial in the physical form of discrete beads or microparticles to orwithin which a soft culture material has been introduced. In oneexample, and without limitation, the stiff culture material can beformed from metal, synthetic polymer, ceramic and the like. In oneexample, and without limitation, the soft culture material can be in thephysical form of a hydrogel or uncrosslinked oligomers of polymerseither synthetic or of natural origin, and the like. In one example, andwithout limitation, the soft culture material can be formed frompolymers of biological origin, synthetic polymers, or combinations ofsynthetic and biological polymers. As one skilled in the art willappreciate, aside from this physical change in the initial physical formof the stiff culture material, the material composition of thisexemplary aspect has the same properties and behavior as the aspectpreviously disclosed.

In yet another aspect, a method of 3D cell passaging is provided thatcomprises providing a population of cells to be passaged and introducingthe population of cells into the material composition, that is comprisedof the combination of stiff and soft tissue cultural materials. In thismethod, it is contemplated that at least a portion of the population ofcells will attach to at least portions of the soft culture material. Itis further contemplated that the cells can attach prior to or afterintroduction of the soft culture material to the stiff culture material.For example, the cells can be encapsulated into a soft culture materialsuch as a hydrogel and thereafter introduced to the stiff culturematerial. In one aspect, it is further contemplated that the “attached”population of cells can be cultured under conditions that are typicalfor the growth of the respective cells, i.e., using appropriatetemperature, humidity, and/or gas exchange. At a desirable and orpredetermined time after the cells attachment, the method can furthercomprise causing the soft culture material to disassociate from thestiff culture material, thereby releasing the soft culture material andthe cells from the stiff culture material of the material composition.In another aspect, the method can further comprise dividing therecovered cells, with or without remnants of the soft culture material,into multiple populations and repeating the method using the subdividedpopulations. It is of course contemplated that this exemplary processcan be done recursively.

In one exemplary aspect of the method of 3D cell passaging, the at leastone cell module can be preloaded with a predetermined quantity ofmaterial composition, such as, the exemplary stiff/soft culture materialcomposition. It is contemplated that the material composition can fillbetween about 5 and 100% of the available space in the cell culturechamber. For example and without limitation, in a configuration having acell culture chamber with a 250 μL volume, a material composition ofbetween 12.5 μL and 250 μL can be utilized. It is also contemplated thatthe exemplary stiff/soft culture material composition can have multipleconfigurations to include, without limitation, providing a materialcomposition that allows for a 3D environment within the at least onecell module of appropriate desired density and surface area to supportgrowth of the particular cells being cultured. Therefore, it iscontemplated that the matrix has the surface area to allow forattachment of the cells as well as the surface area to allow forproliferation of the cells and flow through of any growth factors,nutrients, media, environmental factors, chemokines, chemicals,cytokines, and the like to which it is desired the cells be exposed.Optionally it is contemplated that the exemplary stiff/soft culturematerial composition can provide a material composition that allows fora 3D environment within the at least one cell module of appropriatedesired density, in which the matrix upon which the population of cellsattaches has less free space if it is desirable to maintain a stablecell population rather than proliferating the cell population.

Subsequently, an operator can couple the at least one cell module intothe bioreactor flow circuit and introduce the population of cells intothe at least one cell module. After introduction of the cells and theattachment to the soft culture material of the material composition, thecells can then be cultured in the at least one cell module for a desiredand or predetermined period of time to effect either doubling ormaintenance of the introduced population of cells. It is contemplatedthat, during the culture process, the operator can affect cell behavior(e.g. differentiation, growth, metabolite, vector production, and thelike) by using media containing specific soluble factors, such as, forexample and without limitation, inorganic salts, amino acids, vitamins,ribonucleosides, deoxyribonucleosides, and the like, that can encouragea desired outcome.

Upon the desired and or predetermined period of time expiring, theoperator can introduce a trigger or stimulus designed to disassociatethe soft culture material from the stiff culture material of thematerial composition. In this aspect, the soft culture material can beconfigured or otherwise have a means for releasing the soft culturematerial from the stiff culture material. In one exemplary aspect, thereleasing means can comprise chemical degradation or other changeinitiated by light, temperature, pH, chemical catalyst, and the like.Therefore, it is contemplated that the operator triggered stimulus cancomprise, without limitation, chemical stimuli, i.e., introduced intomedia supplied to the at least one cell module, pH stimuli, thermalstimuli, i.e., for soft culture material of the material compositionconfigured to fall apart or otherwise degrade upon increase or decreasein temperature, light stimuli, and like stimuli. Next, the operator cancollect cells and soft culture material fragments downstream of the atleast one cell module. Optionally, the operator can separate the cellsfrom the soft material fragments or can allow the cells and the softculture materials to remain unseparated.

Optionally, it is contemplated that the collected cells can, if desired,comprise cells that can be divided to form a plurality of “new”populations of cells that can be subsequently individually introducedinto separate cell modules that are preloaded with the materialcomposition, such as, for example, the exemplary soft/stiff materialcomposition. It is contemplated that the “new” population(s) of cellscan be introduced into/onto the soft culture material prior tointroduction of the soft culture material to the stiff culture material.For example, the “new” population(s) of cells can be encapsulated in asoft culture material such as a hydrogel.

It is contemplated that at least portions of the material compositioncan be recycled. For example, if the stiff culture material forming aportion of the material composition is valuable, e.g., a metal, thespent cell module can be recycled. In one non-limiting example, it iscontemplated that the stiff culture scaffold of the material compositioncould be recovered from the spent cell module, cleansed, and thensubsequently preloaded into a cell module for future use.

EXAMPLES 3D Cell Passaging Experiment

Herein provides an example of a method by which cells are cultured invitro, expanded, released from a 3D soft-stiff composite scaffold viadigestion and captured (passaged) for purposes of reseeding intoadditional 3D culture vessels. This method removes the need to culturethe cells in traditional two-dimensional (2D) conditions such as Petridishes and well plates, which has been shown to result innon-physiologically relevant cell response and function. Additionally,3D passaging permits the continuous culture of cells in a closed systemover longer durations while maintaining the cells' natural phenotype andfunction.

Materials and Methods

Culture Chamber: 3DKUBE™ 3D Cell Culture Plasticware—IndependentChambers Configuration (KIYATEC Inc., Pendleton, S.C.)

Scaffold: A soft-stiff composite scaffold was fabricated consisting of“stiff” polystyrene (PS) struts with interconnected porosity and “soft”hyaluronic acid (HA) hydrogel filling the interconnected porosity. ThePS porous scaffold consisted of a stacked crosshatch of 300 μm diameterfibers forming an average 400 μm pore size. Overall dimensions of the PSporous scaffold were 5 mm in diameter and 1.8 mm in thickness. The PSscaffold was placed in the bottom of a well of a 96-well plate. A volumeof 50 μL of methacrylated HA at 2% w/v including 12959 photoinitiatorwas pipetted into the porosity of the PS scaffold. The HA wascrosslinked for 6.5 minutes at approximately 10 mW/cm². The well platewas incubated at 37° C. and 95% RH for one hour to further crosslink the“soft” HA hydrogel within the porosity of the “stiff” PS scaffold. Theentire soft-stiff composite scaffold was frozen for two hours followedby overnight lyophilization to create porosity in and around thecontracted HA hydrogel and PS struts.

Cells: SHEP (human neuroblastoma) cell line transfected with aluciferase expressing gene (SHEP-Luc)

Results and Discussion

The soft-stiff composite scaffold was stored under vacuum at 20° F. toprevent rehydration of the lyophilized HA hydrogel component. Uponcommencing the study, a single soft-stiff (HA-PS) scaffold was placed inthe culture chamber of a special white opaque 3DKUBE IndependentChambers configuration. The inlet and outlet ports of the 3DKUBE werecapped with standard male luer plugs. Prior to assembling the 3DKUBEmodules, the soft-stiff scaffold was seeded with a 100 μL cellsuspension of SHEP-Luc cells (1.0E+5) in Dulbecco's Modified EagleMedium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 1%penicillin-streptomycin. Seeding was done by pipetting the cellsuspension directly onto the soft-stiff scaffold, covering the open 3Dculture chamber in a 60 mm plastic culture dish and allowing cellattachment under static conditions for two hours. Following the two hourstatic period, the remaining seeding medium was gently removed and thecomplete 3DKUBE was assembled and connected to the syringe pump flowcircuit consisting of a 10 mL syringe, platinum-cured silicone tubing,standard luer connectors and a gas exchange reservoir bag. The completeflow circuit, including the assembled 3DKUBE, was primed slowly by handand connected to the syringe pump to commence 50 μL/min volumetric flowrate. A total of 10 mL of DMEM was used for the duration of the 5 dayexperiment.

Samples were prepared and evaluated via Hoechst 33258 dye at time pointsof Day 2 and Day 5. Upon completion of the respective culture period(two or five days), a 3 mL syringe was used to manually inject 500 μL of40 units/mL hyaluronidase digestion solution (608 units/mghyaluronidase) in PBS into the 3D culture chamber via the luer port.Following slow perfusion of the digestion solution into the 3D culturechamber, the system was incubated under periodic agitation (manualinfusion and withdrawal) for 4 hours to digest the “soft” HA portion ofthe soft-stiff composite scaffold. Following digestion, the contents ofthe 3D culture chamber (i.e., the dissociated cells and soft culturematerial) were gently drawn off into the 3 mL syringe to model theconcept of 3D cell passaging. The stiff culture material remained in theculture chamber. The resulting cell suspension of cells and soft culturematerial was placed in a microcentrifuge tube and spun down to collectthe cell pellet. The cell pellet was stored dry at −80° C. followed byHoechst 33258 dye evaluation to quantify the seeding efficiency. A rangeof known cell quantities were cultured, frozen and evaluated in parallelwith experimental samples to provide a correlative standard curve forconversion of fluorescent units to cell number.

Samples were resuspended in 400 μL ddH2O and incubated for one hour at37° C. followed by storage again at −80° C. and then thawed to roomtemperature. A volume of 100 μL of each sample were transferred (induplicate) to a black, clear bottom 96-well plate. 100 μl of HoechstReagent (Invitrogen FluoReporter Blue Fluorometric dsDNA QuantificationKit) was then added to each well before reading the fluorescence using aWallac Victor² 1420 fluorescent plate reader with a 355 nm excitationfilter and a 460 nm emission filter.

The 3D culture demonstrated an increasing numerical trend from Day 2 toDay 5 of the study (FIG. 6). Cells were successfully recovered from the3D soft-stiff composite scaffold via digestion and perfusion via theluer ports. Additional cells were found to remain within the “soft” HAscaffold following the 4 hour digestion procedure suggesting arecommended increase in the digestion period to recover more cells.Ultimately, the study provides a relevant example of 3D cell passagingusing the 3DKUBE™ 3D Cell Culture Plasticware in combination with asoft-stiff composite scaffold useful to the art of cell and tissueculture.

What is claimed is:
 1. A bioreactor system for 3D passaging of cells,comprising: at least one cell module defining a first cell culturechamber, an inlet, an outlet, and a port opening, wherein the portopening is on one end of the cell culture chamber; and a materialcomposition comprising two or more materials, wherein the two or morematerials comprises a stiff culture material and a soft culture materialthat is introduced thereon to the stiff culture material, and whereinthe material composition is loaded therein the at least one cell module.2. The bioreactor system of claim 1, wherein the stiff culture materialhas a porosity between 50μιη and 2 mm.
 3. The bioreactor system of claim1, wherein the stiff culture material is made from metal, ceramic,glass, or a synthetic polymer.
 4. The bioreactor system of claim 1,wherein the soft culture material comprises a polymer of biologicalorigin, a synthetic polymer, or both.
 5. The bioreactor system of claim4, wherein the soft culture material is a hydrogel or uncrosslinkedoligomers of polymers.
 6. The bioreactor system of claim 5, furthercomprising a cell encapsulated in the hydrogel.
 7. The bioreactor systemof claim 1, wherein the soft culture material releases from the stiffculture material by chemical degradation, light exposure, change intemperature, change in pH, or exposure to a chemical catalyst.
 8. Thebioreactor system of claim 1, wherein the stiff culture material iscomposed of beads or microparticles.
 9. The bioreactor system of claim1, wherein the stiff culture material comprises a porous matrix.
 10. Thebioreactor system of claim 1, wherein the soft culture material isintroduced into or onto the stiff culture material prior to being loadedinto the bioreactor system.
 11. The bioreactor system of claim 10,wherein a cell is introduced onto the soft culture material andencapsulated in a hydrogel prior to introduction into or onto the stiffculture material.
 12. The bioreactor system of claim 1, wherein the softculture material is introduced into or onto the stiff culture materialafter being loaded into the bioreactor system.
 13. A method of 3D cellpassaging in a bioreactor system, comprising: providing a population ofcells to be passaged; and introducing the population of cells into amaterial composition comprising two or more materials, wherein the twoor more materials comprises a stiff culture material and a soft culturematerial that is introduced thereon to the stiff culture material and towhich the cells attach.
 14. The method of claim 13, wherein the cellsare introduced into the soft culture material prior to introduction ofthe soft culture material to the stiff culture material.
 15. The methodof claim 13, further comprising causing the soft culture material todisassociate from the stiff culture material.
 16. The method of claim15, further comprising isolating the cells and soft culture materialfrom the material composition.
 17. The method of claim 15, furthercomprising recovering the dissociated cells and dividing the cells intomultiple populations.
 18. The method of claim 17, further comprisingintroducing one or more divided cells into a second bioreactor system.19. The method of claim 18, wherein the cells are introduced into thesecond bioreactor system by introducing the cells into the materialcomposition.
 20. The method of claim 18, wherein the cells areintroduced into the second bioreactor system by introducing the cellsinto a second material composition contained comprising two or morematerials, wherein the two or more materials comprises a stiff culturematerial and a soft culture material that is introduced thereon thestiff culture material to which the cells attach to at least portions ofa soft culture material.
 21. The method of claim 19, wherein the cellsare introduced into the soft culture material prior to introduction ofthe soft culture material to the stiff culture material.